Around the world, countries are trying to push up their vaccination rates to stamp out the threat of tragic, now-preventable diseases like measles.

But there's a surprising corner of the globe where vaccination rates are dismal: New York City private schools.

New York Magazine's Daily Intelligencer obtained vaccination records from the New York State Department of Health and found that "245 New York City private schools fell short of the 95 percent vaccination rate which experts say prevents measles from spreading."

125 [schools] had rates below 90 percent, and 37 fell below 70 percent. The nine private schools with the lowest rates — between 41.5 percent and 18.4 percent — were so underimmunized that if any one of them somehow seceded and became a Sealand-style micro-nation, it would literally have had the worst measles vaccination rate in the world, according to WHO numbers.

It's important to note that this is one area where perfection is actually possible — some schools have vaccination rates that are 100%.

In fact, vaccine exemptions are still quite rare. Nationwide, the median exemption rate for kindergarteners is 1.8%, according to the CDC. The problem, the CDC notes, is that "low vaccination and high exemption levels can cluster within communities, increasing the risk for disease."

That seems to be what we're seeing in some New York City private schools.

Around the world, the success of measles vaccination programs "resulted in a 78% drop in measles deaths between 2000 and 2012," WHO reported. (Measles still kills approximately 100,000 people every year.)

"There is evidence of an increase in vaccine refusal in the United States and of geographic clustering of refusals that results in outbreaks," researchers warned in the New England Journal of Medicine in 2009.

Parents of New York City private school children may want to consider all the people around the world who have died for want of a vaccine which is, luckily, readily available in New York.

Vaccines are one of the major public health victories of the 20th century, but they don't work if people refuse them.